Fe3O4-decorated MXene for the effective removal of 133Ba and 137Cs: synthesis, characterization, and optimization via response surface methodology (RSM)†
‡*a
Vipul Vilas
Kusumkar,
‡b
Michal
Galambos,
b
Eva
Viglasova,
b
Martin
Motola
a
and
Olivier
Monfort
*a
Abstract
In this study, a composite material consisting of MXenes (Ti3C2Tx) and Fe3O4 in the ratio of 70 : 30 w/w% (MXF-30) was synthesized via solvothermal method. The material was characterized using powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller measurements (BET) to understand the relationship between the structure and properties for radionuclide removal (133Ba and 137Cs). Batch experiments employing Box–Behnken design (BBD) were conducted to investigate the impacts of operating parameters such as initial pH, contact time, and initial concentration of Ba2+ and Cs+ ions (containing radiotracers 133Ba and 137Cs). The optimized conditions suggested by BBD were found to be pH 5.5, 240 min contact time, and 0.1 mol L−1 radionuclides. Under these conditions, the experimental values and values predicted from the models for maximum adsorption capacity were in agreement, i.e., 4.18 and 4.07 mmol g−1 for Ba2+ and 6.34 and 6.12 mmol g−1 for Cs+ ions, respectively. The results of studies in a solution containing a mixture of ions (Na+, K+, Ca2+, Co2+, and Mg2+) confirmed that pH 5.5 and 8.0 are suitable for Cs+ and Ba2+ adsorption, respectively. In addition, MXF-30 showed higher affinity for Cs+ due to increased interlayer spacings via the encapsulation mechanism. The typical mechanism of the adsorption of Ba2+ and Cs+ ions was proposed to be a combination of encapsulation (physisorption) and surface complexation (chemisorption).
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